So I was trying to follow helljumper's "new" tf2 modeling tut (beta import) and instead of making a hat I decided I'd make a mask. I am currently at the point where I need to assign the mask to the bip headbone (or maybe some other bone??) but when I do exactly what he did in the video, for some reason the mask relocates to somewhere behind the rig, on the "floor"

Please help me as quick as you can.